#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 1e4 + 5;

int n, k;
int a[N];
bool check(int x) {
  ll cnt = 0;
  rep(i, 1, n) cnt += a[i] / x;
  return cnt >= k;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> k;
  rep(i, 1, n) {
    double x;
    cin >> x;
    a[i] = x * 100;
  }
  int l = 1, r = 1e8;
  while (l <= r) {
    int mid = (l + r) / 2;
    if (check(mid))
      l = mid + 1;
    else
      r = mid - 1;
  }
  double ans = r / 100.0;
  cout << fixed << setprecision(2) << ans;
  return 0;
}